1. Field of the Invention
The present invention relates to a fuel tank valve device for adjusting the internal tank pressure of a fuel tank and a fuel tank ventilation device.
2. Description of the Related Art
A fuel tank ventilation device using this type of fuel tank valve device is disclosed in Japanese Patent No. 4035022. Specifically, the A fuel tank ventilation device is equipped with a full tank control valve and a rollover valve mounted on the top part of the fuel tank, a canister connected via an external path to the full tank control valve and rollover valve, and a check valve provided on the external path connected to the rollover valve. The full tank control valve closes after fulfill fuel, and the rollover valve ensures ventilation to the outside by a float rising and falling according to the fuel fluid level within the fuel tank and also prevents outflow of fuel from the fuel tank when the vehicle is tilted and the like. Also, the check valve prevents the tank internal pressure from going to a preset value or greater and also prevents overfilling during fueling by opening at two stages when the internal pressure of the fuel tank rises.
However, with the fuel tank ventilation device, there was the problem that it is not possible to sufficiently prevent overfilling during fueling.